Unit 2 Information Theory for Cybersecurity Notes | HTCS401 Notes | Aktu Notes
Secrecy
Secrecy in cybersecurity ensures that sensitive information remains confidential and inaccessible to unauthorized parties.
Examples:
- Encryption of messages using cryptographic algorithms like AES (Advanced Encryption Standard) ensures that only authorized recipients can decrypt and read the information.
- Secure communication protocols such as TLS (Transport Layer Security) protect data transmitted over networks from eavesdropping.
Authentication
Authentication verifies the identity of users or entities to ensure they have legitimate access to resources or systems.
Examples:
- Password-based authentication requires users to enter a correct password to access their accounts.
- Biometric authentication uses unique physical characteristics like fingerprints or facial features to verify identity.
Secret Sharing
Secret sharing divides a secret into multiple parts distributed among different participants, where a subset of them can reconstruct the original secret.
Examples:
Shamir's Secret Sharing Scheme divides a secret into shares distributed among participants, ensuring that a specified number of shares are required to reconstruct the secret.
Optimistic Results on Perfect Secrecy
Perfect secrecy ensures that intercepted ciphertext provides no information about the plaintext without the decryption key, regardless of computational power or time.
Example:
The Vernam Cipher, or one-time pad, achieves perfect secrecy by using a random key that is at least as long as the message and never reused.
Secret Key Agreement
Secret key agreement protocols enable two parties to establish a shared secret key over an insecure communication channel.
Example:
Diffie-Hellman key exchange protocol allows two parties to generate a shared secret key securely over a public channel without sharing the secret key directly.
Unconditional Security
Unconditional security ensures that a cryptographic system remains secure even against adversaries with unlimited computational resources.
Example:
One-time pads provide unconditional security when used correctly, as they are impossible to break even with unlimited computational power.
Quantum Cryptography
Quantum cryptography utilizes principles of quantum mechanics to secure communication channels.
Example:
Quantum key distribution (QKD) protocols like BB84 use quantum properties to detect eavesdropping attempts, ensuring secure key exchange.
Randomized Ciphers
Randomized ciphers introduce randomness into encryption processes to enhance security against cryptographic attacks.
Example:
RSA encryption with random padding adds randomness to plaintext before encryption, preventing attackers from predicting patterns in ciphertext.
Types of Codes: Block Codes
Block codes encode fixed-length blocks of data, adding redundancy to detect and correct errors.
Example:
Hamming codes are block codes that add parity bits to data blocks, enabling error detection and correction in digital communication.
Hamming and Lee Metrics
Metrics used in coding theory to measure the distance between codewords.
Example:
Hamming distance measures the number of differing bits between two codewords, crucial for error detection and correction in coding schemes.
Description of Linear Block Codes
Linear block codes are error-correcting codes where any linear combination of codewords remains a valid codeword.
Example:
The Hamming code is a linear block code that corrects single-bit errors and detects two-bit errors using parity bits.
Parity Check Codes
Parity check codes use parity bits to detect errors in data transmission.
Example:
Even parity adds a parity bit to data to ensure the total number of 1s (including the parity bit) is even, providing simple error detection.
Cyclic Code
Cyclic codes are linear block codes with a cyclic shift property, facilitating efficient error detection and correction.
Example:
CRC (Cyclic Redundancy Check) codes are cyclic codes widely used in data communication to detect errors in transmitted data.
Masking Techniques
Masking techniques hide sensitive data by altering or obscuring its representation.
Examples:
- Data masking replaces sensitive information like credit card numbers with tokens or pseudonyms in databases to protect privacy.
- Masking techniques are also used in cryptographic algorithms to obscure intermediate values and prevent side-channel attacks.
These notes cover essential topics in information theory for cybersecurity, providing foundational knowledge on securing information, cryptographic protocols, and error-correcting codes used to enhance data integrity and privacy in digital systems.
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